Authentication processing using a password is performed in various devices, such as personal computers, mobile phones, automated teller machines (ATMs) of banks, and various types of integrated computers. In such devices, when a password mismatch has occurred a specified number of times, processing such as password invalidation and stopping authentication during the day of the password mismatch is performed in some cases. This inhibits a malicious third party from discovering a password by trial and error and achieving unauthorized access to a device. Reducing the specified number results in improvement in security level. It is, however, conceivable that a legitimate user repeatedly enters an incorrect password. Therefore, the convenience of a user would be impaired if the specified number is excessively reduced.
There is known a personal information transaction device in which the relationship between each digit and the next digit in a touch panel is stored, and if the number of times a user presses the next digit by mistake is within a permissible range, that number of times is not included in the count of the specified number and the user is allowed to again input a password.
There is also known a password verification device in which if an input password contains an incorrect entry and the incorrect entry matches the immediately previous incorrect entry, the incorrect entry is not counted.
The above personal information transaction device determines on the basis of a key arrangement in an input unit whether an incorrect entry is a mere incorrect entry. It is, therefore, impossible in some cases to sufficiently enhance convenience. This is because characters and digits that are likely to be incorrectly input vary depending on users, and not all the characters and digits located next to each other are likely to be incorrectly input. Also, keys located next to each other include both those that are likely to be incorrectly input and those that are not.
Also, the above password verification device simply does not count an incorrect entry on the basis of the relationship to an incorrect entry made immediately before. This does not sufficiently reflect characters and digits that are likely to be incorrectly input by a user. For this reason, it is impossible in some cases to sufficiently enhance convenience.
Japanese Laid-open Patent Publication No. 9-212723 and Japanese Laid-open Patent Publication No. 2011-59880 disclose examples of the related art.